I expect that if they followed the same training as you had, they would be able to fly them just as well. Pilots of your era were not genetically or biologically superior to pilots of today
No, not biologically superior, but they had quite a few large transport piston/turboprop hours under their belt prior to moving to jets....3-4000 hours in most cases.
In short, a good deal more handling experience than what you find today, especially in Europe, where 250 hour 'wonders' can be found.
These folks succeed simply because modern transport jets have been manufactured with the poor flying qualities of yesterdays jets, designed out, from the start.
Nothing more, nor less.